We examined life history traits (e.g., mean length-at-age, growth rate, age-at-maturity) for blacktip sharks collected from two separate geographical areas (eastern Gulf of Mexico and South Atlantic Bight) to address the potential for separate stocks in southeastern US waters. Samples were obtained from fishery-dependent and independent sources. Growth and logistic models were fitted to observed length-at-age and reproductive data, respectively. von Bertalanffy growth parameters derived for blacktip shark from the Gulf of Mexico show that they attain a statistically smaller theoretical maximum length (L∞ = 141.6 cm vs. L∞ = 158.5 cm for female and L∞ = 126.0 cm FL and L∞ = 147.4 cm FL for male) and have a faster growth rate (k = 0.24 yr-1 vs. k = 0.16 yr-1 for female and k = 0.27 yr-1 vs. k = 0.21 yr -1 for male) than conspecifics in the South Atlantic Bight. Median length- and age-at-maturity were significantly different between sex and area. Length at which 50% of the population is mature was 117.3 cm FL for females and 103.4 cm FL for males in the Gulf of Mexico and 126.6 cm FL for females and 116.7 cm FL for males in the South Atlantic Bight. Median age-at-maturity was 5.7 yrs and 4.5 yrs for females and males in the Gulf of Mexico, respectively, while age-at-maturity was 6.7 yrs for females and 5.0 yrs for males for sharks from the South Atlantic Bight. Due to varying statistical results, temporal problems of sampling, and potential for gear bias, we could not definitively conclude that differences in life history characteristics exist.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science